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-   -   Rubber Band Balsa Plane -> RC Conversion (http://www.Wattflyer.com/forums/showthread.php?t=62475)

Electrolight 06-10-2011 07:32 AM

Rubber Band Balsa Plane -> RC Conversion
 
Just joined wattflyer. Long time reader first time poster. So, hello.

Long story short:
I need help tissue covering my plane. I used aero gloss to shrink and shine and seal at the same time it shined and sealed and didn't shrink... I have only done the elevator what should I do to get a full shrink. Also, what glue should I use to attach the tissue... Ive heard so much different stuff that now I don't know which glue to use... I also was told that doing anything to seal your tissue can make it heavy. Is this true? I know it will add some weight but is it negligible or is it very heavy?


Long story long:
So I wanted to fly around a little RC airplane around the park or a gymnasium or something. I thought a Dumas piper cub walnut scale balsa wood kit would be small, fun to build and I could engineer it to be RC. Oh and one more thing... It had to be 4 channels... I didn't care how "difficult" it would be that was a must.

So new to the whole airplane RC thing. (I understand very well how they work but never actually flew or held one (other than an aero ace if that even counts...)). So at first I thought I could build my little airplane with 3 9g servos, a 20g esc, and a 25g rimfire motor, and a 49g 800mah 7.4v lipo, with my light 2.4ghz futaba reciever onboard... Well after I weighed all the parts in the kit the whole plane weighed 20g give or take... so I thought it was interesting that the electronics would be almost 7.1 times heavier than the rest of the plane...

So I realized ok thats not going to work... I downgraded to 2.5g servos and a 12g volcano esc (they were sold out of the 6g one I wanted) and a 8.5g brushless motor with supposedly about 80-110g of torque and a 32g 400 mah 7.4v lipo, depending on the propeller (hey maybe I could do 3d?)... anyways... the electronics are going to be about 4 times heavier... thats a little better right?

So I built it and its coming along very well but after so much time. I'm pretty patient but were on roughly the 30th hour and I justtt finished the framework... And to be honest, in retrospect it wasn't even difficult or complicated (ok sometimes when I was tired it was complicated) but I guess I either am slow or I was looking into perfection too much...

the whole plane is basically waiting on the 3 servo's to come in (which should be here in 3 days). I even added all the pushrods and the ailron twistrods? lol But ya I'm really happy with my framework. I even added a massive hatch on the bottom so that I have access to all electronics. The cowl has a nice hatch in case I need to replace the motor. I also am loving the smoothness of the ailrons, I thought they would be stiff but the du-bro micro ailron set works just swell.

Anyways, so I tried to cover the elevator, I figured If I mess up oh well because its much less important than the wings (covering wise). But I decided to use aero gloss to shrink the tissue and shine and seal it but 10 minutes later (the stuff dries seems to dry fast) it is still wrinkled :/ It was rather taught before I tried it... any tips? what glue should I use on the tissue? I also was told that doing anything to your tissue can make it heavy... "just use water and call it a day"... Is this true?

Also, assuming my moter is actually rated at 80g this thing should fly... but when it does, is it going to screech across the sky just to stay afloat or will it be a surlily enjoyable flight? any thoughts?

So ya... I'm mostly a flyer but I love building things so I thought Id give it a shot... I wasn't expecting 35+ hours... so ya if I don't get any tips then I'll make sure this thing fly's, even if its only once... rocketry style :cool:


Thanks for the help

CHELLIE 06-10-2011 08:40 AM

Hi :ws: and Welcome to Wattflyers, do you live in a area that has a lot of humidity ???? thats the only reason i can see for the dope not wanting to tighten up the tissue paper, or is the dope old and thick ???? I never had a problem with tissue paper getting to tighten up on my planes, but i dont live in a area that has high humidity, make a testing frame or 2 and try to thin the dope with thinner a little, maybe that might help the dope to dry faster and pull tight, did you spray the paper first with water and stretch it on the wood part before applying the dope ???? just wondering, gee, I have not doped a plane in over 45 years :eek: :D Take care and have fun, Chellie


http://www.ehow.com/how_4448705_cove...-airplane.html

JetPlaneFlyer 06-10-2011 09:59 AM

You should use water spray to shrink the tissue.. Mist the untreated tissue with water and leave to dry and it should tighten up nicely. If I get any creases then i usually give the area a lick:p>.. spit seems to work even better than water. Water wont work if you have painted it..the painted tissue will have to come off.

Once it's all taught then seal with NON-SHRINK DOPE or some now use water based sealer like 'Future' brand spray wooden floor sealer.. Personaly i use old fashioned dope but you must use the non or low shrink type and thin it 50:50

To attach it i prefer to use PVA wood glue slightly thinned with water.

It's best to use coloured tissue and not bother with paint as this saves considerable weight (every fraction of a gram counts) but you can get away with paint if you spray in a very light coat... Dont even think about brushing on paint, it will be much too heavy.

Weight is absolutely critical on these small planes. Even the gear you have now is much too heavy. You should be better looking at something like a Spektrum 'brick' (AR6400BL for instance) which has ESC, servos and receiver built into one unit which weighs only a few grams. Then add a single cell Lipo of about 150mAh (3-4g) and maybe a 5g motor and you have a full electrics package for about 15 - 20g.. and that's about as much as this type of plane can cope with to be honest.

If you want to use the gear you have in a lightweight balsa model then you should look at something quite a bit bigger.


Steve

Rockin Robbins 06-10-2011 02:07 PM

I always used clear dope to stick tissue to balsa, water shrunk it, sometimes twice and then with 50-50 mix of clear dope and thinner doped the tissue. I never sprayed it, but if I had I would have saved some weight there.

Good luck with your build! Would love to see some photos.

JetPlaneFlyer 06-10-2011 04:15 PM

Just to confirm.. your gear is still much too heavy. Your Cub model is 17.5" span.. that's a little smaller than the Parkzone Ultra Micro Piper Cub

Given the lightweight structure involved then you need to aim for a similar slow flying performance as that of the PZ Cub.. That can only mean aiming for a weight similar to the PZ Cub...

The PZ Cub weighs 29g ready to fly including battery! With the gear you have in mind you will be lucky to bring the model in below 100g.. thats between 3 and 4 times heavier than the (slightly larger) PZ Cub.

Sure, with enough power it might 'fly', sort of, but it wont survive the first landing.

I'd get a bigger airframe, one of the 30" dumas kits would be more appropriate for the gear you have.

Sorry to be a killjoy:oops:

Steve

Electrolight 06-15-2011 06:22 AM

I got the tissue issue figured out... cover... wet... dry... dope... dry is the order... but I stopped using the dope after only the elevater... It made the elevator 100% water proof but it was also extra weight I didn't think I wanted to add.

Ya I did the math again. I'm looking at roughly 87 grams fully loaded... I think the plane structurally will easily be able to take it... unfortunately I think it will fly like a rocket... But thats fine lol (not really I'm just trying to convince myself)

Im this far into it... I'm going to at least give it a shot... even if it doesn't fly well. Regardless here are the pictures :)

I don't have the money for true micro gear so if this doesn't work at all or not well then I'll just buy a 30" $30 dumas airplane like the mulligan or the beaver and build those.

Electrolight 06-15-2011 06:33 AM

2 Attachment(s)
Here are the pictures I messed up in the last post.

CHELLIE 06-15-2011 07:27 AM

Quote:

Originally Posted by Electrolight (Post 816160)
Here are the pictures I messed up in the last post.

That looks Great :$ I normally wet the tissue first, cover, pull it tight, glue the edges , let dry, then dope it, and it comes out very tight like a drum :) But that might be to tight for your plane and might cause it to warp, Take care and have fun, Chellie


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